Axial entry buckets, i.e., rotor blades, are assembled onto a turbine wheel by sliding the buckets along the rotor axis into mating dovetails on the turbine wheels. In prior assemblies, the turbine buckets have male radially inwardly projecting dovetails for mating engagement with radially inwardly directed female dovetails on the turbine wheel. The wheel dovetails are circumferentially spaced from one another about the wheel. Axial entry buckets on turbine wheels have proven quite satisfactory in assembly and use.
Certain turbine designs, however, require integral covers or shrouds at the bucket tips. Typically the shrouds have overlapping protrusions that nest with shrouds of adjacent buckets. For example, certain shrouds may have a generally Z-shaped configuration when viewed in a radially inward direction. Should the buckets be assembled serially around the wheel using the axial entry dovetail system, the protrusions of adjacent shrouds, typically the first assembled and next to the last assembled buckets, prevent assembly of the last axial entry bucket from either the upstream or downstream sides of the wheel. The blocking shroud protrusions cannot be removed because the shrouds must be in contact with one another to maintain continuous circumferential coupling of the buckets at their tips in use. Consequently, securing the final or closure bucket with its shroud to the otherwise completed wheel assembly by the axial entry assembly method presents a problem.